Fix format for integer amounts (#231)

* support both fractions and integer values

* test fractions

* prettier

src/lib/utils.ts

@@ -28,10 +28,16 @@ export function formatCategoryForAIPrompt(category: Category) {
   return `"${category.grouping}/${category.name}" (ID: ${category.id})`
 }
 
+/**
+ * @param fractions Financial values in this app are generally processed in cents (or equivalent).
+ * They are are therefore integer representations of the amount (e.g. 100 for USD 1.00).
+ * Set this to `true` if you need to pass a value with decimal fractions instead (e.g. 1.00 for USD 1.00).
+ */
 export function formatCurrency(
   currency: string,
   amount: number,
   locale: string,
+  fractions?: boolean,
 ) {
   const format = new Intl.NumberFormat(locale, {
     minimumFractionDigits: 2,
@@ -40,7 +46,7 @@ export function formatCurrency(
     // '€' will be placed in correct position
     currency: 'EUR',
   })
-  const formattedAmount = format.format(amount)
+  const formattedAmount = format.format(fractions ? amount : amount / 100)
   return formattedAmount.replace('€', currency)
 }